#pragma once
#include<iostream>
#include<vector>
using namespace std;

enum State
{
	EXIST,
	EMPTY,
	DELETE
};
template<class K,class V>
struct HashDate
{
	pair<K, V> _kv;
	State _state = EMPTY;
};
template<class K>
struct HashFunc
{
	size_t operator()(const K& key)
	{
		return (size_t)key;
	}
};
template<>
struct HashFunc<string>
{
	size_t operator()(const string& key)
	{
		size_t hash = 0;
		for (auto& e : key)
		{
			hash *= 131;
			hash += e;
		}
		return hash;
	}
};
template<class K,class V,class Hash = HashFunc<K>>
class HashTable
{
public:
	inline unsigned long __stl_next_prime(unsigned long n)
	{
		// Note: assumes long is at least 32 bits.
		static const int __stl_num_primes = 28;
		static const unsigned long __stl_prime_list[__stl_num_primes] =
		{
			53, 97, 193, 389, 769,
			1543, 3079, 6151, 12289, 24593,
			49157, 98317, 196613, 393241, 786433,
			1572869, 3145739, 6291469, 12582917, 25165843,
			50331653, 100663319, 201326611, 402653189, 805306457,
			1610612741, 3221225473, 4294967291
		};
		const unsigned long* first = __stl_prime_list;
		const unsigned long* last = __stl_prime_list +
			__stl_num_primes;
		const unsigned long* pos = lower_bound(first, last, n);
		return pos == last ? *(last - 1) : *pos;
	}
	HashTable()
	{
		_tables.resize(__stl_next_prime(0));
	}

	bool Insert(const pair<K, V>& kv)
	{
		if (Find(kv.first)) {
			return false;
		}
		if ((double)_n / (double)_tables.size() >= 0.7)
		{
			//扩容
			HashTable<K, V> newTH;
			newTH._tables.resize(__stl_next_prime(_tables.size() + 1));
			//将旧表的数据拷贝到新表
			for (int i = 0; i < _tables.size(); i++)
			{
				if (_tables[i]._state == EXIST)
				{
					newTH.Insert(_tables[i]._kv);
				}
			}
			_tables.swap(newTH._tables);
		}

		Hash hs;
		size_t hash0 = hs(kv.first) % _tables.size();
		size_t i = 1;
		size_t hashi = hash0;
		while (_tables[hashi]._state == EXIST)
		{
			// 冲突探测
			hashi = (hash0 + i) % _tables.size();
			++i;
		}
		_tables[hashi]._kv = kv;
		_tables[hashi]._state = EXIST;
		++_n;

		return true;
	}
	HashDate<K, V>* Find(const K& key)
	{
		Hash hs;
		size_t hash0 = hs(key) % _tables.size();
		size_t i = 1;
		size_t hashi = hash0;
		while (_tables[hashi]._state != EMPTY)
		{
			if (_tables[hashi]._state == EXIST && _tables[hashi]._kv.first == key)
			{
				return &_tables[i];
			}
			hashi = (hash0 + i) % _tables.size();
			++i;
		}
		return nullptr;
	}
	bool Erase(const K& key)
	{
		HashDate<K, V>* ret = Find(key);
		if (ret == nullptr) {
			return false;
		}
		else {
			ret->_state = DELETE;
			--_n;
			return true;
		}
	}
private:
	vector<HashDate<K, V>> _tables;
	size_t _n = 0; //表中存储数据的个数
};